1. Field of the Invention
The present invention relates to a high-frequency composite component for use in a high-frequency circuit performing transmission and reception of radio waves in a cellular phone, a pager, or the like, and a portable wireless device incorporating the component.
2. Description of the Related Art
A high-frequency composite component which can satisfy the needs for miniaturization, high performance, and price reduction, is needed for a high-frequency circuit in a portable wireless device such as a cellular phone of the Personal Handy-phone System (PHS) and the Personal Digital Cellular System (PDC). Such a high-frequency composite component is disclosed in Japanese Unexamined Patent Publication No. 7-58586.
FIG. 11 is the top view of the prior art high-frequency composite component. A high-frequency composite component 50 includes a low noise amplifier 52 for amplifying weak radio waves received by an antenna 51, a high-frequency filter 53 for eliminating unnecessary frequency components, and a substrate 54 for mounting these components. The low noise amplifier 52 is constituted of a field effect transistor Q51, capacitors C51 to C53, an inductor L51, and a resistor R51. The high-frequency filter 53 is constituted of surface acoustic wave resonators S51 and S52, and a capacitor C54.
In the prior art high-frequency composite component, however, since the low noise amplifier and the high-frequency filter are mounted on the substrate, a problem is that further reduction in size and weight is difficult.
To overcome the above described problems, embodiments of the present invention provide a high-frequency composite component in which reduction in size and weight and high performance can be achieved, and a portable wireless device incorporating the component.
To this end, according to one aspect of the present invention, there is provided a high-frequency composite component including a high-frequency circuit having an amplifier and a filter, a multi-layer substrate made by laminating a plurality of dielectric layers to integrate the amplifier and the filter with the multi-layer substrate, an amplifier ground, a filter ground, and external terminals formed on the multi-layer substrate. The amplifier ground and the filter ground are separate and are respectively connected to separate external terminals formed on the multi-layer substrate.
In addition, in the above high-frequency composite component, the amplifier may be disposed at the upper part of the multi-layer substrate and the filter may be disposed at the lower part of the multi-layer substrate.
Furthermore, in the high-frequency composite component, an active element and a passive element constituting the amplifier may be mounted on the multi-layer substrate as chip components, and a passive element constituting the filter may be built in the multi-layer substrate as a strip-line electrode or a capacitor electrode.
According to another aspect of the present invention, there is provided a high-frequency composite component including a high-frequency circuit having a mixer and a filter, a multi-layer substrate made by laminating a plurality of dielectric layers to integrate the mixer and the filter with the multi-layer substrate, a mixer ground, a filter ground, and external terminals formed on the multi-layer substrate. The mixer ground and the filter ground are separate and are respectively connected to separate external terminals formed on the multi-layer substrate.
In this high-frequency composite component, an active element and a passive element constituting the mixer may be mounted on the multi-layer substrate, and a passive element constituting the filter may be built in the multi-layer substrate as a strip-line electrode or a capacitor electrode.
According to another aspect of the present invention, a portable wireless device of the invention includes one of the above-described high-frequency composite components.
In the high-frequency composite component of the present invention, the amplifier ground and the filter ground constituting the high-frequency circuit integrated with the multi-layer substrate are separate and are connected to separate external terminals formed on the multi-layer substrate. As a result, the potential of the amplifier ground and the potential of the filter ground can be different.
Additionally, since the mixer ground and the filter ground constituting the high-frequency circuit integrated with the multi-layer substrate are separate and are connected to separate external terminals formed on the multi-layer substrate, leakage of high-frequency signals between the mixer and the filter can be suppressed.
Moreover, since the portable wireless device of the present invention adopts the high-frequency composite component in which oscillation can be suppressed or isolation can be provided, deterioration in the characteristics of the portable wireless device can be prevented.
Other features and advantages of the invention will be understood from the following detailed description of embodiments of the invention with reference to the drawings, in which like references indicate like elements and parts.